Multi-modal transportation refers to the use of multiple modes of transportation in a single journey or trip. This can include a combination of walking, biking, driving, public transportation, and other forms of transportation, such as ride-sharing services or taxis. The goal of multi-modal transportation is to provide users with more flexibility, convenience, and efficiency in their journeys, as well as to reduce congestion, improve traffic flow, and decrease environmental impacts. Researchers in this area study ways to optimize multi-modal transportation networks, improve connectivity between different modes of transportation, and enhance the overall user experience. They may also explore the integration of technology and data analytics to enable seamless and efficient multi-modal transportation systems.